The invention relates to a method of monitoring the operation of a subscriber unit of a telecommunication system. The invention also relates to a subscriber network element of a radio system providing a wireless local loop, the subscriber network element having a data transmission connection with a telephone exchange and comprising means for establishing, via base stations, a radio connection to the subscriber units located in the coverage area of the radio system, for transmitting telecommunication signals between the subscriber units and the exchange.
The invention relates in particular to monitoring the operation of a subscriber unit to be used in a WLL system, i.e. a radio system providing a wireless local loop. In a WLL system, an ordinary two-wire telephone set is connected via a radio connection by means of a special terminal equipment to the local exchange, which in turn is connected to the public telephone network via network cabling. In this connection, a subscriber unit refers to the equipment the subscriber has for transmitting and receiving telecommunication signals, i.e. in case of the WLL system, the subscriber unit comprises a WLL terminal equipment consisting of a radio part and a teleadapter (to which the user interface, e.g. a telephone, is connected), and a user interface, such as a telephone, a telefax terminal, a computer/modem combination or the like, connected to the terminal equipment.
To guarantee the interference-free transfer of telecommunication signals, for example phone calls, it is necessary to monitor subscriber units so that possible malfunctions will be detected as early as possible. It is especially important to monitor WLL subscriber units, since they are more prone to malfunctions than normal subscriber units operating via a cable.